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Interface plays a critical role in determining the electrical properties and thermal management capability of carbon (e.g., nanotubes, graphene) based polymer nanocomposites. The strong interface is usually desirable and realized by forming the covalent interaction between nanocarbon and polymer matrix. However, the pristine properties, such as high electrical and thermal conductivity, of nanocarbon are inevitably deteriorated due to the introduction of lattice defects. In this work, a nondestructive strategy, combining mussel-inspired chemistry and surface initiated reversible addition fragmentation chain transfer (RAFT) polymerization, was developed to prepare lattice defect free interface between carbon nanotubes (CNTs) and epoxy resin. Polydopamine (PDA) was first coated on the CNT surfaces and then polymethyl methacrylate (PMMA) or polyglycidyl methacrylate (PGMA) macromolecular chains were grafted onto PDA encapsulated CNTs, which can result in non-covalent or covalent interface between CNTs and epoxy resin, respectively. It was found that PGMA encapsulated CNTs based epoxy nanocomposites show apparent advantages in increasing dielectric constants and suppressing dielectric loss tangent, as well as enhancing thermal conductivity. This study proves the superiority of the covalent interface formed by nondestructive functionalization in enhancing the dielectric properties and thermal management capability of nanocarbon based polymer composites.

Anode-respiring bacteria (ARB) generate electrical current from the oxidation of short chain fatty acids (SCFA), primarily acetate, in microbial electrolysis cells (MECs). Animal rendering wastewater (RW) has high fat content, which under anaerobic conditions can yield acetate, making RW a potential feed for MECs. Yet, excess intermediate long chain fatty acids (LCFA) may limit conversion of LCFA and SCFA, and impact ARB activity. Here, we evaluated electrical current production in single-chamber MECs fed with RW. In RW-fed MECs, 34.26 ± 2.69% of the COD provided was converted to electrical current in an 80-day batch cycle. LCFA accumulated in RW-fed MECs, during which conversion of acetate to electrical current was limited. Diverse sulfate-reducing microorganisms were present in the anode biofilm in RW-fed MECs, whereas the genus Geobacter dominated in inoculum-only control MECs. Detection of H2-utilizing homoacetogens suggested some internal cycling of H2 produced at the cathode. Overall, this study shows that current production is possible from RW, but to be a viable process for RW treatment, further improvement in rates of COD conversion and current production is necessary along with identifying configurations and/or conditions in which the inhibitory effect of LCFA is reduced.

Anaerobic treatment of high-fat content wastewater could produce significant methane yields, making anaerobic treatment a promising alternative to energy-consuming aerobic treatment. However, accumulated intermediate LCFA may inhibit the conversions of both SCFA to acetate and of acetate further to methane. The effect of feed-to-inoculum ratio was evaluated in biochemical methane potential (BMP) tests for anaerobic digestibility of animal rendering wastewater (RW). Results showed that more than 90% of RW COD was converted during BMP tests with volumetric feed-to-inoculum ratio of 1. Higher feed-to-inoculum ratios led to RW COD conversion efficiencies below 64% and caused lag periods of >6 days in methane production. Degradation of acetate at different time points in relation to conversion of LCFA suggested that LCFA accumulation partially hindered acetate utilization. The methanogenic community shifted from hydrogenotrophic to acetoclastic methanogenesis in moderately-loaded BMPs. At highest feed-to-inoculum ratio of 9, acetoclastic methanogens were severely inhibited. The bacterial genus Syntrophomonas was present in increasing relative abundance with increasing feed-to-inoculum ratio. Increased relative abundance of the genus Desulfovibrio with increasing feed-to-inoculum ratio was likely a response to the high sulfate concentration in RW.